I am refering to:
Greg Ewing schrieb:
> where [w] is a weak reference object. Then you could periodically
> scan the trail looking for dead weakref objects and remove the
> corresponding [*] node from the list.
>
> You can also attach callbacks to weakref objects that are triggered
> when the referenced object dies. You might be able to make use of
> that to remove items from the trail instead of the periodic scanning.
Question to Chris Angelico: If I stay with my
sweep_trail(), which is the periodically scanning,
I can use a single linked list.
On the other hand if I would use the trigger
from Python, I possibly would need a double linked
list, to remove an element.
Chris Angelico, is there a third option, that I have
overlooked? Single linked list uses less space
than double linked list, this why I go with scan.
Chris Angelico schrieb:
On Sun, Sep 19, 2021 at 11:46 AM Mostowski Collapse <burse...@gmail.com> wrote:
Yeah, it seems weak references could indeed spare
me mark_term(). But then I am stil left with sweep_trail().
I did not yet measure what takes more time mark_term()
or sweep_trail(). The displayed "gc" is the sum of both.
From what I have seen, very large trail practically reduced
to a zero trail during Prolog GC, I am assuming that
mark_term() is not the working horse. Usually mark_term()
only marks what is not-Garbage, and sweep_trail()
has to deal with Garbage and not-Garbage. And there
is usually a lot of Garbage, much more than not-Garbage.
Finding the objects that survive, is like finding the needle
in the haystack, except we do not have to scan the
If you stop referring to something, it is garbage. Python will dispose of it.
You literally need to do nothing at all, and let the language take
care of things.
ChrisA
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